Earlier quoted context omitted.
Correct me if I'm wrong but isn't Freeview just a marketing name for DVB-T (or T2 nowadays), which supported encrypted content since its inception and can mix encrypted & non-encrypted channels in the same multiplex?
This is correct but not every TV will have the slot for a decryption card. The UK has good broadband but far from the level of a universal public service. (That would be communism apparently)
Key distribution is already a solved problem as well, the UK has a large userbase of smartcard-based prepayment systems such as for electric/gas meters or transport cards (Oyster card) and every tobacco/liquor store has a terminal that can sell or reload these cards. Expanding this system to reload TV cards is just a software update.